A multidisciplinary group has developed a seam-free, segmented polyurethane blood pump that has been extensively evaluated in a series of normal calves. The pump is capable of handling 10 L/min. and is free of thromboembolic complications. This blood pump has been employed for circulatory support in a series of calves with microsphere-induced left ventricular failure. The pump is capable of supporting the circulation but a high percentage of calves developed ventricular fibrillation between two and four days after the induction of cardiogenic shock. Studies to be performed over the next year will include an evaluation of left atrial to aortic pumping in calves with induced left ventricular failure to evaluate the effect of chronic left atrial bypass on survival rate and myocardial infarction size. A low-speed, high torque, reversing brushless DC motor has been developed to actuate the segmented polyurethane blood pump previously described. The first model has been employed to provide circulatory support to a calf for a period exceeding 3 months. The second generation unit is now being evaluated on the laboratory bench. This unit employs a samarium-cobalt type DC magnet rather than the Alnico unit employed in the first model. Studies over the next year will include animal implantation evaluation of the second model motor-driven pump. Simplification of the electronics and use of a microprocessor control system will form an important part of the motor-driven pump evaluation program. The mechanical left ventricular device will continue to be employed in certain selected patients with heart failure following cardiac operations. In this application, the pump is placed in the paracorporeal location and is pneumatically operated.